Bret Michaels Rushed Into Emergency Surgery

Bret Michaels never made it to the stage Sunday night in San Antonio, Texas.

Moments before he was due to perform at Sea World, doctors urged the former Poison frontman, 47 -- and current Celebrity Apprentice star -- to go to the hospital, his rep confirms to UsMagazine.com. He'd been suffering all day from severe stomach pains and what he thought was the flu.

Adds the rep, "Michaels, who has been known to perform under extreme conditions that would make most performers cancel, will unfortunately have no choice but to reschedule some of his April tour dates."